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Old 2012-10-15, 22:32   #1
davieddy
 
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Default Did that guy actually break the the sound barrier?

What was the speed of sound where he reached 800+ mph?

David
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Old 2012-10-15, 23:23   #2
Batalov
 
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A question of this depth can be only matched by Svejk's riddle.

Quote:
Originally Posted by The Good Soldier Svejk
"Would you know how to calculate the diameter of the globe?"

"No, I'm afraid I wouldn't," answered Svejk, "but I'd like to ask you a riddle myself, gentlemen. Take a three-storied house, with eight windows on each floor. On the roof there are two dormer windows and two chimneys. On every floor there are two tenants. And now, tell me, gentlemen, in which year the house-porter's grandmother died?"
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Old 2012-10-15, 23:28   #3
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http://en.wikipedia.org/wiki/Red_Bull_Stratos#Analysis
Quote:
The FAI announced that confirmation of exact times and altitudes could take several weeks. The data will be evaluated first by the Austrian Aeroclub (ÖAeC) since Baumgartner is an Austrian citizen and will then be confirmed by the FAI. While the reported values may change on verification, there was no doubt that Baumgartner broke the sound barrier.
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Old 2012-10-16, 00:52   #4
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I didn't hear the sonic boom, but I am going mildly deaf.

D
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Old 2012-10-16, 00:58   #5
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Quote:
Originally Posted by Batalov View Post
A question of this depth...
As an ex physics teacher I should be able to remember a formula for the speed of sound
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Old 2012-10-16, 01:03   #6
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c = sqrt(gamma*R*T) for quasi-ideal gases. For air, adiabatic index (= ratio of specific heats c_p/c_v) gamma = 1.4, to a very close approximation. R is the universal gas constant normalized by the molar mass of the gas (or gas mixture) in question.

Since gamma and R are independent of local atmospheric conditions, if you know c at some standard conditions just use the variation as sqrt(T) to compute elsewhere. Colder = lower speed of sound.

Last fiddled with by ewmayer on 2012-10-16 at 01:12
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Old 2012-10-16, 07:36   #7
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Quote:
Originally Posted by ewmayer View Post
c = sqrt(gamma*R*T) for quasi-ideal gases. For air, adiabatic index (= ratio of specific heats c_p/c_v) gamma = 1.4, to a very close approximation. R is the universal gas constant normalized by the molar mass of the gas (or gas mixture) in question.

Since gamma and R are independent of local atmospheric conditions, if you know c at some standard conditions just use the variation as sqrt(T) to compute elsewhere. Colder = lower speed of sound.
10/10 so far.

Now speaking as a non-specialist atmospherical physicist, what was T?

D
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Old 2012-10-16, 15:10   #8
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http://en.wikipedia.org/wiki/Speed_of_sound

In particular look at this graph on that page:
http://en.wikipedia.org/w/index.php?...962.svg&page=1
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Old 2012-10-16, 21:58   #9
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I believe he did indeed break the sound barrier. Fear not, however, the world's best scientists are carefully reconstructing it, and will hopefully finish the repairs by December :)
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Old 2012-10-17, 00:03   #10
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Proposal: "The Human Meteorite" Competition

Next up: Starting with a spacewalk from orbit (any height, it must just be high enough that the original orbit is not rapidly decaying itself) and without the use of any artificial thrusters aside from maneuvering thrusters having a maximum total impulse of (say) 100 Newton-seconds, perform a capsule-less re-entry and descent from space, landing safely on earth. By "capsule-less" let us say wearing a total amount of gear -- including spacesuit, drag chutes and/or gliding apparatus -- of total mass no greater than that of its human wearer.

(I honestly believe some daring soul will accomplish this before the century is out).

The physics of such a re-entry are quite interesting. There are at least 2 or 3 distinct strategies one might employ. Discuss!
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Old 2012-10-17, 00:38   #11
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Quote:
Originally Posted by ewmayer View Post
The physics of such a re-entry are quite interesting. There are at least 2 or 3 distinct strategies one might employ. Discuss!
A ballute would be my guess.
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